A coherent light receiving device, a coherent light receiving method and a system

Abstract

The present application relates to the field of optical communications, and in particular to a coherent optical receiving device, a coherent optical receiving method and a system. The device includes: a signal optical receiving module, a polarization decomposer, a polarization beam splitter and a coherent photoelectric processing module. The signal optical receiving module generates and outputs a first polarization light of a first polarization state and a second polarization light of a second polarization state with polarization states orthogonal to each other according to the source signal light. The polarization decomposer generates and outputs a first local oscillator light whose light intensity in the first polarization state and the second polarization state is not zero according to the source local oscillator light. The polarization beam splitter generates and outputs a third polarization light of a first polarization state and a fourth polarization light of a second polarization state according to the first local oscillator light. The coherent photoelectric processing module performs mixing and photoelectric conversion on the first polarization light, the second polarization light, the third polarization light and the fourth polarization light to output multiple coherent electrical signals. The device and method provided in the present application can solve the polarization fading problem of the local oscillator light in the self-coherent optical communication system.

Description

Technical Field

[0001] The present application relates to the field of optical communications, and in particular to a coherent light receiving device, a coherent light receiving method and a system. Background Art

[0002] With the continuous development of optical communication technology, people have proposed a self-homodyne detection (SHD) technology. In an optical communication system based on SHD technology (for the sake of distinction, the following text will be described as a self-coherent optical communication system), the laser at the optical transmitter will output two beams of light, one of which will be processed into signal light and transmitted to the optical receiver, while the other will be used as local oscillator light and transmitted to the optical receiver. After receiving the signal light and the local oscillator light, the optical receiver can demodulate the signal light through the local oscillator light to obtain the transmission content carried by the signal light. In practical applications, since the local oscillator light and the signal light are of the same origin and have the same carrier phase, the phase noise will cancel each other out during demodulation, which can reduce the line width requirements of the laser, thereby reducing the cost and power consumption of the optical communication system. However, SHD technology has the problem of polarization fading of the local oscillator light. The so-called polarization fading problem of the local oscillator light is that since the polarization state of the local oscillator light after link transmission is unknown, when the polarization beam splitter (PBS) at the optical receiving end needs to split the local oscillator light and mix it with the two polarization states of the signal light (for the convenience of explanation, it is assumed to be the first polarization state and the second polarization state), the polarization beam splitter can only obtain the light component of the first polarization state of the local oscillator light, while the light component of the local oscillator light in the second polarization state is zero. This will cause the optical receiving end to be unable to amplify the signal light in the second polarization state, affecting its subsequent coherent reception of the signal light and degrading the transmission performance of the self-coherent optical communication system.

[0003] In the prior art, polarization tracking solutions or polarization perturbation solutions are usually used to solve the polarization fading problem of local oscillator light. However, both solutions require the addition of active devices such as photoelectric detectors (PDs), digital signal processors (DSPs) or phase modulators in the optical receiving end and the implementation structure is complex, which will increase the cost and power consumption of the optical receiving end, thereby reducing the applicability and practicality of the self-coherent optical communication system. Summary of the invention

[0004] In order to solve the above problems, the present application provides a coherent optical receiving device, a coherent optical receiving method and a system, which can solve the fading problem of local oscillator light existing in the self-coherent optical communication system with low cost and low power consumption, and can improve the applicability and applicability of the self-coherent optical communication system.

[0005] In the first aspect, an embodiment of the present application provides a coherent light receiving device. The coherent light receiving device includes a signal light receiving module, a polarization decomposer, a polarization beam splitter, and a coherent photoelectric processing module. The coherent photoelectric processing module is connected to the signal light receiving module and the polarization beam splitter, respectively, and the polarization decomposer is connected to the polarization beam splitter. The signal light receiving module is used to receive the source signal light, and generate and output a first polarization light in a first polarization state and a second polarization light in a second polarization state according to the source signal light. Wherein, the first polarization state is orthogonal to the second polarization state. The polarization decomposer is used to receive the source local oscillator light, and generate and output a first local oscillator light according to the source local oscillator light. Wherein, the light intensity of the first local oscillator light in the first polarization state and the second polarization state is not zero. The polarization beam splitter is used to receive the first local oscillator light, and generate and output a third polarization light in the first polarization state and a fourth polarization light in the second polarization state according to the first local oscillator light. The coherent photoelectric processing module is used to receive the first polarized light, the second polarized light, the third polarized light and the fourth polarized light, and perform frequency mixing and photoelectric conversion on the first polarized light, the second polarized light, the third polarized light and the fourth polarized light to output a plurality of coherent electrical signals.

[0006] In the above implementation, the source local oscillator light is first converted into the first polarized light whose light intensity is not zero in the first polarization state and the second polarization state by the polarization decomposer, and then the third polarized light and the fourth polarized light whose light intensity is not zero are obtained by polarization splitting by the polarization beam splitter. In this way, even if the polarization state of the source local oscillator light is unknown, the polarization beam splitter will not be unable to split the two polarized lights due to the polarization fading of the local oscillator light, which effectively solves the fading problem of the local oscillator light in the self-coherent optical transmission system, and can improve the applicability and applicability of the self-coherent optical communication system.

[0007] In combination with the first aspect, in a feasible implementation, the polarization decomposer includes a substrate, and N1 polarization decomposition components arranged on a first plane of the substrate. The first plane is a plane of the substrate facing away from the polarization beam splitter. N1 is a positive integer greater than or equal to 1. When the source local oscillator light irradiates the first plane, the N1 polarization decomposition components are used to radiate the first local oscillator light to the polarization beam splitter. Each of the N1 polarization decomposition components is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

[0008] In the above implementation, a substrate and N1 polarization decomposition components are used to form a polarization decomposer, which has a simple structure and is easy to implement, so that the cost of designing and producing the polarization decomposer is low, thereby solving the polarization fading problem of the local oscillator light in the self-coherent optical communication system at a low cost.

[0009] In combination with the first aspect, in a feasible implementation, any polarization decomposition component of the N1 polarization decomposition components includes a first metal antenna and a second metal antenna. One end of the first metal antenna is connected to one end of the second metal antenna. When the source local oscillator light irradiates the first plane, the first metal antenna is used to radiate the light field of the first polarization state to the polarization beam splitter, and the second metal antenna is used to radiate the light field of the second polarization state to the polarization beam splitter.

[0010] In the above implementation, two connected metal antennas are used to form a single polarization decomposition component, so that the entire polarization decomposer is a passive optical device, which can improve the device stability of the polarization decomposer and reduce its power consumption, thereby achieving a low-power and low-cost solution to the polarization fading problem of the local oscillator light existing in the coherent optical receiving device, and improving the applicability and practicality of the entire self-coherent optical communication system.

[0011] In combination with the first aspect, in a feasible implementation, the first metal antenna and the second metal antenna are perpendicular to each other on the first plane. In this way, the polarization decomposition component can fully convert the light component of the source local oscillation light it receives into a light field of the first polarization state and a light field of the second polarization-normal state, thereby improving the conversion efficiency of the polarization decomposition group and reducing light loss.

[0012] In combination with the first aspect, in a feasible implementation manner, the axial lengths of the first metal antenna and the second metal antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

[0013] In combination with the first aspect, in a feasible implementation manner, a transmittance of the substrate for light of the first wavelength is equal to or greater than a preset transmittance.

[0014] In combination with the first aspect, in a feasible implementation, the polarization decomposer includes a metal film, a first metal waveguide and a second metal waveguide arranged on the second plane of the metal film, and N2 nanoslot antenna groups etched on the first metal waveguide and / or the second metal waveguide. N2 is a positive integer greater than or equal to 1, and the second surface is the surface of the metal film facing the polarization beam splitter. The first metal waveguide and the second metal waveguide are parallel to each other on the second surface. When the source local oscillation light irradiates the end faces of the first metal waveguide and the second metal waveguide, the first metal waveguide and the second metal waveguide are used to receive and conduct the source local oscillation light, and the N2 nanoslot antenna groups are used to radiate the first local oscillation light to the polarization beam splitter. Among them, each of the N2 nanoslot antenna groups is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

[0015] In the above implementation, the double-ridge waveguide structure constructed by the metal film, the first metal waveguide and the second metal waveguide receives and conducts the source local oscillation light, and then the N2 nanoslot antenna groups etched on the first metal waveguide and / or the second metal waveguide convert the first local oscillation light, thereby realizing the function of the polarization decomposer. This implementation method is relatively simple and has a passive structure, which can make the cost and power consumption of the polarization decomposer low. Therefore, the polarization fading problem of the local oscillation light in the self-coherent optical communication system can be solved at low cost and low power consumption, which can improve the applicability and practicality of the entire self-coherent optical communication system.

[0016] In combination with the first aspect, in a feasible implementation, any one of the nanoslot antenna groups includes a first nanoslot antenna and a second nanoslot antenna that are perpendicular to each other on the second surface. When the first metal waveguide and the second metal waveguide conduct the source local oscillation light, the first nanoslot antenna is used to radiate the light field of the first polarization state to the polarization beam splitter, and the second nanoslot antenna is used to radiate the light field of the second polarization state to the polarization beam splitter.

[0017] In the above implementation, two mutually perpendicular nanoslot antennas are used to form a nanoslot antenna group, which is simple and easy to implement, and can further reduce the design and production costs of the polarization decomposer.

[0018] In combination with the first aspect, in a feasible implementation, the distance between the first nanoslot antenna and the second nanoslot antenna on the second plane is a target preset distance, and the light intensity of the light field of the first polarization state radiated by the first nanoslot antenna is the same as the light intensity of the light field of the second polarization state radiated by the second nanoslot antenna. In this way, the light intensity of the first local oscillation light in the first polarization state and the second polarization state can be the same, which can facilitate the subsequent frequency mixing processing of the coherent optoelectronic processing module.

[0019] In combination with the first aspect, in a feasible implementation manner, the sizes of the first nanoslot antenna and the second nanoslot antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

[0020] In combination with the first aspect, in a feasible implementation, the coherent optical receiving device further includes a first optical interface and a second optical interface. The first optical interface is connected to one end of the polarization decomposer, and the other end of the polarization decomposer is connected to the polarization beam splitter through the second optical interface. The first optical interface is used to focus the received source local oscillator light and transmit the focused source local oscillator light to one end of the polarization decomposer, and the second optical interface is used to focus the received first local oscillator light and transmit the focused first local oscillator light to the polarization beam splitter.

[0021] In the above implementation, light transmission is performed through an optical interface with a light focusing function, which can reduce light loss caused by transmission through a spatial light field.

[0022] In a second aspect, an embodiment of the present application further provides a coherent optical communication method. The method is applicable to the coherent optical receiving device described in the first aspect above. The coherent optical receiving device includes: a signal light receiving module, a polarization decomposer, a polarization beam splitter, and a coherent photoelectric processing module, the coherent photoelectric processing module is respectively connected to the signal light receiving module and the polarization beam splitter, and the polarization decomposer is connected to the polarization beam splitter. The method includes: receiving the source signal light through the signal light receiving module, generating and outputting a first polarization light in a first polarization state and a second polarization light in a second polarization state according to the source signal light. Wherein, the first polarization state is orthogonal to the second polarization state. Receive the source local oscillator light through the polarization decomposer, and generate and output the first local oscillator light according to the source local oscillator light. Wherein, the light intensity of the first local oscillator light in the first polarization state and the second polarization state is not zero. Receive the first local oscillator light through the polarization beam splitter, and generate and output the third polarization light in the first polarization state and the fourth polarization light in the second polarization state according to the first local oscillator light. The first polarized light, the second polarized light, the third polarized light and the fourth polarized light are received by a coherent photoelectric processing module, and the first polarized light, the second polarized light, the third polarized light and the fourth polarized light are mixed and photoelectrically converted to output a plurality of coherent electrical signals.

[0023] In combination with the second aspect, in a feasible implementation, the polarization decomposer includes a substrate, and N1 polarization decomposition components arranged on a first plane of the substrate, wherein the first plane is a plane of the substrate facing away from the polarization beam splitter. N1 is a positive integer greater than or equal to 1. When the source local oscillator light irradiates the first plane, the first local oscillator light is radiated to the polarization beam splitter through the N1 polarization decomposition components, wherein each of the N1 polarization decomposition components is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

[0024] In combination with the second aspect, in a feasible implementation, each of the N1 polarization decomposition components includes a first metal antenna and a second metal antenna, and one end of the first metal antenna is connected to one end of the second metal antenna. The light field of the first polarization state is radiated to the polarization beam splitter through the first metal antenna of each polarization decomposition component in the N1 polarization decomposition components, and the light field of the second polarization state is radiated to the polarization beam splitter through the second metal antenna of each polarization decomposition component in the N1 polarization decomposition components, so as to radiate the first local oscillation light to the polarization beam splitter. In combination with the second aspect, in a feasible implementation, the first metal antenna and the second metal antenna are perpendicular to each other on the first plane.

[0025] In combination with the second aspect, in a feasible implementation manner, the axial lengths of the first metal antenna and the second metal antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

[0026] In combination with the second aspect, in a feasible implementation, the polarization decomposer includes a metal film, a first metal waveguide and a second metal waveguide arranged on the second plane of the metal film, and N2 nanoslot antenna groups etched on the first metal waveguide and / or the second metal waveguide. N2 is a positive integer greater than or equal to 1, the second surface is the surface of the metal film facing the polarization beam splitter, and the first metal waveguide and the second metal waveguide are parallel to each other on the second surface. When the source local oscillation light irradiates the end faces of the first metal waveguide and the second metal waveguide, the source local oscillation light is received and conducted by the first metal waveguide and the second metal waveguide, and the first local oscillation light is radiated to the polarization beam splitter through the N2 nanoslot antenna groups, wherein each of the N2 nanoslot antenna groups is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

[0027] In combination with the second aspect, in a feasible implementation, each of the N2 nanoslot antenna groups includes a first nanoslot antenna and a second nanoslot antenna that are perpendicular to each other on the second surface. The light field of the first polarization state is radiated to the polarization beam splitter through the first nanoslot antenna of each nanoslot antenna group in the N2 nanoslot antenna groups, and the light field of the second polarization state is radiated to the polarization beam splitter through the second nanoslot antenna of each nanoslot antenna group in the N2 nanoslot antenna groups, so as to radiate the first local oscillation light to the polarization beam splitter.

[0028] In combination with the second aspect, in a feasible implementation, the distance between the first nanoslot antenna and the second nanoslot antenna on the second plane is a target preset distance, and the light intensity of the light field of the first polarization state radiated by the first nanoslot antenna is the same as the light intensity of the light field of the second polarization state radiated by the second nanoslot antenna.

[0029] In combination with the second aspect, in a feasible implementation manner, the sizes of the first nanoslot antenna and the second nanoslot antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

[0030] In combination with the second aspect, in a feasible implementation, the coherent light receiving device further includes a first optical interface and a second optical interface, wherein the first optical interface is connected to one end of the polarization decomposer, and the other end of the polarization decomposer is connected to the polarization beam splitter through the second optical interface. The received source local oscillator light is focused through the first optical interface to obtain the focused source local oscillator light. The focused source local oscillator light is received through the polarization decomposer. The received first local oscillator light is focused through the second optical interface and the focused first local oscillator light is output. The focused first local oscillator light is received through the polarization beam splitter.

[0031] In a third aspect, an embodiment of the present application further provides a coherent optical receiving device. It includes: a coherent optical receiving device as described in any one of the first aspects above, and an optical signal processor coupled to the coherent optical receiving device. In actual use, the optical signal processor is used to receive multiple coherent electrical signals output by the coherent optical receiving device, and determine the transmission content carried by the source signal light based on the multiple coherent electrical signals.

[0032] In a fourth aspect, an embodiment of the present application further provides a self-coherent optical communication system. The self-coherent optical communication system comprises an optical transmitting device, an optical fiber, and a coherent optical receiving device as described in any one of the first aspects above. The optical transmitting device generates and transmits source local oscillator light and source signal light to the coherent optical receiving device through the optical fiber. The coherent optical receiving device receives the source local oscillator light and the source signal light through the optical fiber, and determines the transmission content carried on the source signal light based on the source local oscillator light and the source signal light.

[0033] The solutions provided in the second to fourth aspects are used to implement or cooperate with the coherent optical receiving device provided in the first aspect, and thus can achieve the same or corresponding beneficial effects as the first aspect, and will not be described in detail here.

[0034] In summary, the coherent optical receiving device and the coherent optical receiving method provided in the embodiments of the present application can solve the fading problem of the local oscillator light existing in the sub-coherent optical communication system with low cost and low power consumption, and can improve the applicability and applicability of the self-coherent optical communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a self-coherent optical communication system provided in an embodiment of the present application;

[0036] Figure 2 It is a structural schematic diagram of a coherent optical receiving device provided in an embodiment of the present application;

[0037] Figure 3 is a schematic structural diagram of a polarization decomposer provided in an embodiment of the present application;

[0038] Figure 4 is another structural schematic diagram of a polarization decomposer provided in an embodiment of the present application;

[0039] Figure 5 It is another structural schematic diagram of a coherent optical receiving device provided in an embodiment of the present application;

[0040] Figure 6 It is another structural schematic diagram of a coherent optical receiving device provided in an embodiment of the present application;

[0041] Figure 7 It is a flow chart of a coherent light receiving method provided in an embodiment of the present application;

[0042] Figure 8 It is a structural schematic diagram of a coherent optical receiving device provided in an embodiment of the present application;

[0043] Fig. 9 It is a structural schematic diagram of another self-coherent optical communication system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] The device form and business scenario described in the embodiments of the present application are intended to more clearly illustrate the technical solution of the embodiments of the present application, and do not constitute a limitation on the technical solution provided by the embodiments of the present application. A person skilled in the art will appreciate that, with the evolution of device forms and the emergence of new business scenarios, the technical solution provided by the embodiments of the present application is also applicable to similar technical problems.

[0045] The technical solution proposed in this application can be applied to different business scenarios, including but not limited to: backbone optical transmission network, optical access network, short-distance optical interconnection, long-distance optical interconnection and wireless business fronthaul / backhaul, etc.

[0046] See also Figure 1 , Figure 1 Schematic diagram of a self-coherent optical communication system provided in an embodiment of the present application. Figure 1 As described above, the self-coherent optical communication system may include an optical transceiver 10 and an optical transceiver 11 coupled by a signal optical fiber 12 and a local oscillator optical fiber 13. In practical applications, the optical transceiver 10 and the optical transceiver 11 are mutually opposite optical transceivers, and the two can simultaneously send and receive optical signals to each other, so the two can provide two-way communication in the self-coherent optical communication system. Figure 1As shown, the optical transceiver 10 may specifically include a light source 101, an optical splitter 102, an optical modulation module 103, a signal processor 104, a coherent receiver 105, a filter 106, and a filter 107. The optical transceiver 11 may specifically include a light source 111, an optical splitter 112, an optical modulation module 113, a signal processor 114, a coherent receiver 115, a filter 116, and a filter 117. It is now assumed that the optical transceiver 10 is configured to output a local oscillator optical signal and a modulated optical signal of a wavelength λ1 and receive a local oscillator optical signal and a modulated optical signal of a wavelength λ2, and the optical transceiver 11 is correspondingly configured to output a local oscillator optical signal and a modulated optical signal of a wavelength λ2 and receive a local oscillator optical signal and a modulated optical signal of a wavelength λ1. In the actual optical signal transmission and reception process, the light source 101 in the optical transceiver 10 can be used to provide continuous light at a wavelength λ1. Then the continuous light at the wavelength λ1 is decomposed by the spectrometer 102 into a local oscillator light signal at the wavelength λ1 and a carrier light signal at the wavelength λ1. It should be noted here that in the embodiment of the present application, the light output by the light source without any processing is collectively referred to as continuous light, and the light processed by the spectrometer or the optical modulation module is collectively referred to as an optical signal. For example, the light output by the light source 101 is the continuous light of wavelength λ1, and the light decomposed by the spectrometer 102 is the local oscillator light signal of wavelength λ1 and the carrier light signal of wavelength λ1. It should be understood that the above setting is only for the convenience of understanding and distinguishing the light before and after the processing operation such as spectrometry or optical modulation, and does not have other limiting functions. Then, the local oscillator light of wavelength λ1 is selected by the filter 107 and output to the local oscillator optical fiber 13, and the carrier light signal of wavelength λ1 is output to the optical modulation module 103. Then, the optical modulation module 103 can optically modulate the carrier optical signal of wavelength λ1 according to the information to be transmitted provided by the signal processor 104 (for the convenience of distinction, the first information to be transmitted will be used instead of the description below) to obtain the modulated signal light of wavelength λ1. Then, the modulated optical signal of wavelength λ1 is selected by the filter 106 and transmitted to the signal optical fiber 12. Then, the local oscillator optical fiber 13 can transmit the local oscillator light of wavelength λ1 to the optical transceiver 11, and the signal optical fiber 12 can transmit the modulated optical signal of wavelength λ1 to the optical transceiver 11. In addition, the filter 107 can also receive the local oscillator optical signal of wavelength λ2 from the optical transceiver 11 from the local oscillator optical fiber 13, and select to transmit the local oscillator light of wavelength λ to the coherent receiver 105. At the same time, the filter 106 can receive the modulated optical signal of wavelength λ2 from the optical transceiver 11 from the signal optical fiber 12, and select to transmit the modulated optical signal of wavelength λ2 to the coherent receiver 105.After acquiring the modulated optical signal of wavelength λ2 and the local oscillator optical signal of wavelength λ2, the coherent receiver 105 can demodulate the modulated optical signal of wavelength λ2 according to the local oscillator optical signal of wavelength λ2 to obtain the information to be transmitted carried by the modulated optical signal of wavelength λ2 (for the convenience of distinction, the second information to be transmitted will be used instead of the description below), and transmit the second information to be transmitted to the signal processor 104. Here, the filter 107 is mainly used to separate the local oscillator light of wavelength λ1 and the local oscillator light of wavelength λ2, and select the transmission of these two local oscillator lights of different wavelengths to different devices. The filter 106 is mainly used to separate the signal light of wavelength λ1 and the signal light of wavelength λ2, and select the transmission of these two signal lights of different wavelengths to different devices. At this point, the optical transceiver 10 has completed the transmission of the first information to be transmitted and the reception of the second information to be transmitted. Similarly, each device in the optical transceiver 11 can also perform the functions performed by the corresponding devices in the optical transceiver 10 to complete the transmission of the modulated optical signal and the local oscillator optical signal at the wavelength λ2, and receive the modulated optical signal and the local oscillator optical signal at the wavelength λ1, thereby completing the reception of the first information to be transmitted and the sending of the second information to be transmitted.

[0047] In such Figure 1 In the actual operation of the self-coherent optical communication system shown in the figure, since the local oscillator light and the signal light have the same source and the same carrier phase, the phase noise will cancel each other out during demodulation, which can reduce the line width requirements of the laser and further reduce the cost and power consumption of the optical communication system. SHD technology has brought obvious advantages to the self-coherent optical communication system, but it also introduces a difficult problem to solve, namely the polarization fading problem of the local oscillator light. Figure 1Taking the coherent receiver 115 in the figure as an example, in actual use, after receiving the signal light from the optical transceiver 10, the coherent receiver 115 needs to split the signal light into two polarized light states (here it is assumed to be the first polarization state and the second polarization state) through a polarization beam splitter (PBS) (here it is assumed to include polarized light L1 of the first polarization state and polarized light L2 of the second polarization state). Among them, the first polarization state and the second polarization state are orthogonal. After receiving the local oscillator light from the optical transceiver 10, the coherent receiver 115 also needs to split the local oscillator light into two polarized light beams (here it is assumed to be polarized light L3 of the first polarization state and polarized light L4 of the second polarization state) through a polarization beam splitter. Then, the coherent receiver 115 needs to mix and photoelectrically convert the polarized light L1 and the polarized light L3, and mix and photoelectrically convert the polarized light L2 and the polarized light L4, so as to obtain multiple coherent electrical signals. Here, the multiple coherent electrical signals are used for the subsequent demodulation of the signal light by the optical receiving end 11 to obtain the transmission content carried by the signal light. The so-called polarization fading problem of the local oscillator light, that is, because the polarization state of the local oscillator light after the link transmission is unknown, when the polarization beam splitter of the coherent receiver 115 needs to polarize the local oscillator light and mix it with the two polarization states of the signal light respectively, the polarization beam splitter can only obtain the above-mentioned polarization light L3, and the light intensity of the polarization light L4 is zero. This situation will cause the coherent receiver 115 to be unable to perform correct mixing and photoelectric conversion subsequently, affecting the subsequent demodulation of the signal light by the coherent receiver 115, and deteriorating the transmission performance of the self-coherent optical communication system.

[0048] In the prior art, in order to solve the polarization fading problem of local oscillator light in the sub-coherent optical transmission system, people have proposed solutions such as polarization tracking solutions or polarization perturbation solutions. However, these solutions all require the addition of active devices such as photodetectors, digital signal processors or phase modulators in the optical receiving end and the implementation structure is complex, which will increase the cost and power consumption of the optical receiving end, thereby reducing the applicability and practicality of the self-coherent optical communication system.

[0049] Therefore, the technical problem to be solved by this application is: how to solve the polarization fading problem of local oscillator light with low cost and low power consumption, and then optimize the transmission performance of the self-coherent optical communication system, and improve the applicability and applicability of the self-coherent optical communication system.

[0050] In order to solve the above problems, the present application provides a coherent light receiving device, a coherent light receiving method and a self-coherent optical communication system, which can solve the polarization fading problem of local oscillator light with low cost and low power consumption, and can improve the applicability and applicability of the self-coherent optical communication system.

[0051] Embodiment 1

[0052] See below Figure 2 , Figure 2 20 is a schematic diagram of a coherent light receiving device provided in an embodiment of the present application. The coherent light receiving device 20 can replace the above Figure 1 The coherent receiver 105 or the coherent receiver 115 shown in the figure can realize the corresponding functions. In order to facilitate the subsequent description of the functions of the coherent optical receiving device 20, it is assumed here that in the actual optical transmission process, the coherent optical receiving device 20 is a device for receiving the source local oscillator light and the source signal light of the first wavelength. Figure 2 As shown, the coherent optical receiving device 20 may include a signal optical receiving module 21, a polarization decomposer 22, a polarization beam splitter 23 and a coherent optical processing module 24. The coherent optical processing module 24 is connected to the signal optical receiving module 21 and the polarization beam splitter 23 respectively, and the polarization decomposer 22 is connected to the polarization beam splitter 23.

[0053] In the actual light receiving process, when the source signal light and the source local oscillator light from the opposite end are transmitted to the coherent light receiving device 20, the signal light receiving module 21 can receive the above-mentioned source signal light, and then generate and output two polarized light beams with orthogonal polarization states to the coherent photoelectric processing module 24 according to the source signal light. Here, for the convenience of distinction, it is assumed that the two polarized light beams with orthogonal polarization states include a first polarized light of a first polarization state and a second polarized light of a second polarization state, and the first polarization state and the second polarization state are orthogonal. The above-mentioned polarization decomposer 22 can receive the above-mentioned source local oscillator light, and then generate and output a processed source local oscillator light to the polarization beam splitter 23 according to the source local oscillator light (for the purpose of distinction, the first local oscillator light will be used instead of the description below). Among them, the light intensity of the above-mentioned first local oscillator light in the above-mentioned first polarization state and the second polarization state is not zero. The above-mentioned polarization beam splitter 23 can receive the above-mentioned first local oscillator light, and then generate and output the third polarized light of the first polarization state and the fourth polarized light of the second polarization state to the coherent photoelectric processing module 24 according to the first local oscillator light. The coherent photoelectric processing module 24 is used to receive the first polarized light, the second polarized light, the third polarized light and the fourth polarized light, and then mix and photoelectrically convert the first polarized light, the second polarized light, the third polarized light and the fourth polarized light to output a plurality of coherent electrical signals. Here, the plurality of coherent electrical signals carry transmission content, and the plurality of coherent electrical signals can be further processed by the signal processor included in the optical transceiver to complete the demodulation of the source signal light, so as to finally obtain the transmission content.

[0054] It should be understood here that the connection between the two optical devices described in the present application may refer to a physical connection, such as an optical connection established by a waveguide or other optical transmission device, or may refer to a spatial optical connection, such as an optical connection established by a spatial light field. For example, the polarization decomposer 22 and the polarization beam splitter 23 may be connected through a spatial light field, that is, the first local oscillation light output by the polarization decomposer 22 may be directly radiated to the polarization beam splitter 23 to achieve the transmission of the first local oscillation light to the polarization beam splitter 23. For another example, the polarization beam splitter 23 and the coherent optoelectronic processing module 24 may be connected through two polarization-maintaining optical fibers, and then the third polarized light and the fourth polarized light generated by the polarization beam splitter 23 may be transmitted to the coherent optoelectronic processing module 24 through the two polarization-maintaining optical fibers. In the embodiments of the present application, the specific connection method between each device or module may be set according to the actual application requirements of each device, and the present application does not limit this.

[0055] In the above implementation, the source local oscillator light is first converted into the first polarized light whose light intensity is not zero in the first polarization state and the second polarization state by the polarization decomposer 22, and then polarization splitting is performed by the polarization beam splitter 23 to obtain the third polarized light and the fourth polarized light whose light intensity is not zero. In this way, even if the polarization state of the source local oscillator light is unknown, the polarization beam splitter 23 will not be unable to split the light into two polarized lights due to the polarization fading of the local oscillator light, which effectively solves the fading problem of the local oscillator light in the self-coherent optical transmission system, and can improve the applicability and applicability of the self-coherent optical communication system.

[0056] For some possible implementations, see Figure 3 , Figure 3 Schematic diagram of the structure of a polarization decomposer provided in an embodiment of the present application. Figure 3 As shown, the polarization decomposer 22 may specifically include a substrate 221, and N1 polarization decomposition components 222 arranged on the first plane of the substrate 221. Here, the above-mentioned first plane is the plane of the substrate 221 facing away from the polarization beam splitter 23 (it can also be understood as the side of the substrate 221 irradiated by the source local oscillation light), and the above-mentioned N1 is an integer equal to or greater than 1. It should be noted here that in actual applications, the source local oscillation light is directly irradiated on the first plane of the substrate 221, and then converted into the first local oscillation light under the spatial light field through the action of N1 polarization decomposition components 222 and the substrate 221, and irradiated on the polarization beam splitter 23. That is, the source local oscillation light is transmitted to the polarization decomposer 22 through the spatial light field, and the first local oscillation light converted by the polarization decomposer 22 is also transmitted to the polarization beam splitter 23 in the form of a spatial light field. Therefore, in this implementation, the connection relationship between the polarization decomposer 22 and the polarization beam splitter 23 is the spatial optical connection described above.

[0057] In the actual light receiving process, the source local oscillator light received by the coherent light receiving device 20 from the opposite end will be directly irradiated on the above-mentioned first plane. The N1 polarization decomposition components 222 on the first plane can be used as an optical antenna, and under the irradiation of the source local oscillator light, the converted first local oscillator light will be radiated in the direction of the polarization beam splitter 23. Among them, each of the above-mentioned N1 polarization decomposition components 222 will radiate the light field of the first polarization state and the light field of the second polarization state in the direction of the polarization beam splitter 23. In other words, under the irradiation of the source local oscillator light, each of the above-mentioned N1 polarization decomposition components 222 will receive a part of the light component of the source local oscillator light, and then due to the characteristics of the optical antenna, under the action of this part of the light component, each polarization decomposition component will radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter 23, and the light field of the first polarization state and the light field of the second polarization state radiated by each polarization decomposition component are combined into the first local oscillator light transmitted to the polarization beam splitter 23 through the spatial light field.

[0058] Preferably, in actual design, in order to reduce the light loss generated by the polarization decomposer 22, the transmittance of the substrate 221 for the light of the first wavelength is also equal to or greater than a preset transmittance threshold. That is, the substrate 221 should have a high transmittance for the source local oscillation light. Specifically, the substrate 221 can be a transparent substrate made of glass or other materials.

[0059] Preferably, in actual design, in order to improve the conversion efficiency of the polarization decomposer 22, the emission direction of the source local oscillation light should be perpendicular to the first plane, that is, the source local oscillation light should be vertically irradiated on the first plane. In order to improve the transmission efficiency of the first local oscillation light between the polarization decomposer 22 and the polarization beam splitter 23, the first plane should also be perpendicular to the direction of the optical port on the polarization beam splitter 23 for receiving the first local oscillation light, that is, the first local oscillation light should be vertically irradiated on the optical port on the polarization beam splitter 23 for receiving the first local oscillation light.

[0060] In the above implementation, a substrate 221 and N1 polarization decomposition components 222 are used to form a polarization decomposer 22, which has a simple structure and is easy to implement, so that the cost of designing and producing the polarization decomposer 22 is relatively low, thereby solving the polarization fading problem of the local oscillator light in the self-coherent optical communication system at a low cost.

[0061] The following will take any polarization decomposition component 223 among the N1 polarization decomposition components 222 as an example to describe in detail the specific structure and function of each polarization decomposition component among the N1 polarization decomposition components.

[0062] For further information, please see Figure 3 ,like Figure 3As shown, the polarization decomposition component 223 may specifically include a first metal antenna 2231 and a second metal antenna 2232. The first metal antenna 2231 and the second metal antenna 2232 are fixedly arranged on the first plane of the substrate 221. The axial direction of the first metal antenna 2231 (for the convenience of distinction, the first axial direction will be used instead of the description below) and the axial direction of the second metal antenna 2232 (for the convenience of distinction, the second axial direction will be used instead of the description below) are parallel to the first plane. In terms of spatial position, one end of the first metal antenna 2231 should be connected to one end of the second metal antenna 2232 to form a double-arm structure with an angle. In this double-arm structure, the axial angle (here assumed to be a) formed by the first metal antenna 2231 and the second metal antenna 2232 should be greater than 0 degrees and less than 180 degrees, that is, this double-arm structure can be an L-shaped or V-shaped structure. From the working principle of the metal antenna, it can be known that a metal antenna responds to only one polarization state, and the first metal antenna 2231 and the second metal antenna 2232 form a double-arm structure, so that no matter what the polarization state of the source local oscillator light is, it can be responded to by the double-arm structure formed by the first metal antenna 2231 and the second metal antenna 2232, that is, the polarization decomposition component 223 composed of the first metal antenna 2231 and the second metal antenna 2232 can respond to the source local oscillator light of any polarization state.

[0063] It should be noted here that the axial lengths of the first metal antenna 2231 and the second metal antenna 2232 can be specifically determined by the first wavelength of the source local oscillator light and the source signal light. In other words, the values ​​of the axial lengths of the first metal antenna 2231 and the second metal antenna 2232 can be specifically empirical values ​​obtained by conducting multiple experiments on metal antennas of different lengths based on the size of the first wavelength and the first polarization state and the second polarization state that the polarization decomposition component 223 needs to support. The first metal antenna 2231 and the second metal antenna 2232 designed with the empirical value can radiate light fields of the first polarization state and the second polarization state under the action of the first wavelength of light. It should be understood that the embodiment of the present application does not impose specific restrictions on the shape and size of the metal antenna involved (such as the first metal antenna 2231 and the second metal antenna 2232 mentioned above). Metal antennas of any shape and size that can radiate light fields of the first polarization state or the second polarization state toward the polarization beam splitter 23 under the action of the first wavelength of light are within the protection scope of the present application.

[0064] In the actual light receiving process, when the source local oscillation light received by the coherent light receiving device 20 is irradiated on the polarization decomposition component 223, the electric dipole modes of the first metal antenna 2231 and the second metal antenna 2232 can be excited, and then the first metal antenna 2231 will absorb a part of the light component of the source local oscillation light, and under the action of this part of the light component, radiate the light field of the first polarization state to the polarization beam splitter 23. Similarly, the second metal antenna 2232 will also absorb a part of the light component of the source local oscillation light, and under the action of this part of the light component, radiate the light field of the second polarization state to the polarization beam splitter 23.

[0065] Optionally, the first metal antenna 2231 and the second metal antenna 2232 may be a rectangular parallelepiped or cylindrical structure. The first metal antenna 2231 and the second metal antenna 2232 may be made of gold, silver, etc., which is not specifically limited in the present application.

[0066] Preferably, the axial angle a between the first metal antenna 2231 and the second metal antenna 2232 is 90 degrees, that is, the double-arm structure is an L-shaped structure, that is, the first metal antenna 2231 and the second metal antenna 2232 are perpendicular to each other on the first plane. In this way, the polarization decomposition component 223 can fully convert the light component of the source local oscillation light it receives into the light field of the first polarization state and the light field of the second polarization-normal state, which can improve the conversion efficiency of the polarization decomposition component 223 and reduce light loss.

[0067] Combined with the above description of the structure and function of the polarization decomposition component 223, in a specific implementation, each of the N1 polarization decomposition components 222 can adopt the same structure as the polarization decomposition component 223, and can also achieve the same function as the polarization decomposition component 223. Therefore, in the actual light receiving process, each polarization decomposition component will radiate the light field of the first polarization state and the light field of the second polarization state toward the polarization beam splitter 23, so that the polarization decomposer 22 can radiate the first local oscillation light to the polarization beam splitter 23.

[0068] It should be noted that, in a specific implementation, each of the N1 polarization decomposition components 222 can be evenly distributed on the first plane. For example, the N1 polarization decomposition components can be arranged on the first plane in the form of a rectangular, regular hexagonal or circular array. Preferably, the N1 polarization decomposition components should be arranged in an array that can make the first local oscillation light have the same light intensity in the first polarization state and the second polarization state, which can facilitate the subsequent frequency mixing processing of the coherent optoelectronic processing module 24.

[0069] In the above implementation, two connected metal antennas are used to form a polarization decomposition component, so that the entire polarization decomposer 22 is a passive optical device, which can improve the device stability of the polarization decomposer 22 and reduce its power consumption, thereby achieving a low-power and low-cost solution to the polarization fading problem of the local oscillator light existing in the coherent optical receiving device 20, and improving the applicability and practicality of the entire self-coherent optical communication system.

[0070] For some possible implementations, see Figure 4 , Figure 4 is another structural schematic diagram of a polarization decomposer provided in an embodiment of the present application. Figure 4 As shown, the polarization decomposer 22 may specifically include a metal film 224, a first metal waveguide 225, a second metal waveguide 226, and N2 nanoslot antenna groups 227 etched on the first metal waveguide 225 and / or the second metal waveguide 226. Wherein, the above N2 is an integer greater than or equal to 1. Figure 4 As shown, in order to facilitate the specific description of the spatial structure of the polarization decomposer 22, a three-dimensional spatial coordinate system is introduced, including an x-axis, a y-axis and a z-axis. Among them, the plane formed by the x-axis and the y-axis is the second plane itself or a plane parallel to the second plane. The z-axis is perpendicular to the x-axis and the y-axis respectively. Here, this second plane is the plane of the metal film 224 facing the polarization beam splitter 23. These three coordinate axes correspond to three directions in space, which are assumed to be the x-direction, the y-direction and the z-direction respectively. In the actual design, the first metal waveguide 225 and the second metal waveguide 226 are placed in parallel on the second plane of the metal film 224, and the third axial direction of the first metal waveguide 225 and the fourth axial direction of the second metal waveguide 226 are parallel to the y-direction. The N2 nanoslot antenna groups 227 are etched on the surface of the first metal waveguide 225 and / or the second metal waveguide 226 facing the polarization beam splitter 23. It should be noted that the N2 nanoslot antenna groups 227 may be all etched on the first metal waveguide 225, or all etched on the second metal waveguide 226, or partly etched on the first metal waveguide 225 and the other part etched on the second metal waveguide 226. The present application does not impose any specific restrictions on this. In actual work, the source local oscillation light reaches the end surfaces of the first metal waveguide 225 and the second metal waveguide 226 through the spatial light field (for example, Figure 4 The first end face of the first metal waveguide 225 and the second end face of the second metal waveguide 226 are shown in the figure), and then the first local oscillation light processed by the polarization decomposer 22 is also transmitted to the polarization beam splitter 23 through the spatial light field. Therefore, in this implementation, the connection relationship between the polarization decomposer 22 and the polarization beam splitter 23 is also the spatial optical connection described above.

[0071] It should also be noted that, since a single ridge waveguide structure on the metal film can support a waveguide mode with a single fixed polarization state, the double-ridge waveguide structure composed of the first metal waveguide 225, the second metal waveguide 226 and the metal film 224 can support waveguide modes with two fixed polarization states, so that no matter what the polarization state of the source local oscillation light is, it can be fully received and conducted by the double-ridge waveguide structure composed of the first metal waveguide 225, the second metal waveguide 226 and the metal film 224. In addition, the size (such as length, width, height, etc.) of the first metal waveguide 225 and the second metal waveguide 226 and the distance between the first metal waveguide 225 and the second metal waveguide 226 on the second plane are determined by the size of the first wavelength of the source local oscillation light and the types of two polarization states that the double-ridge waveguide structure needs to support. That is to say, the sizes of the first metal waveguide 225 and the second metal waveguide 226 and the distance between the first metal waveguide 225 and the second metal waveguide 226 on the second plane may be empirical values ​​obtained by conducting multiple experiments on the double-ridge waveguide structure based on the size of the first wavelength and the types of two polarization states that the double-ridge waveguide structure needs to support. Therefore, the embodiment of the present application does not specifically limit the sizes of the first metal waveguide 225 and the second metal waveguide 226 and the distance between the first metal waveguide 225 and the second metal waveguide 226 on the second plane to the size of the first wavelength of the source local oscillation light.

[0072] In the actual light receiving process, the source local oscillation light signal received by the coherent light receiving device 20 will be irradiated on the first end face of the first metal waveguide 225 and the second end face of the second metal waveguide 226 through the spatial light field, and the first metal waveguide 225 and the second metal waveguide 226 on the metal film 224 will receive and conduct the source local oscillation light in the y direction. When the source local oscillation light is transmitted through the first metal waveguide 225 and the second metal waveguide 226, due to the scattering effect of the metal edge, the resonance of the above-mentioned N2 nanoslot antenna groups 227 will be stimulated, thereby causing the above-mentioned N2 nanoslot antenna groups to radiate the first polarized light in the direction of the polarization beam splitter 23 (that is, the z direction). Among them, each of the above-mentioned N2 nanoslot antenna groups 227 will radiate the light field of the first polarization state and the light field of the second polarization state in the z direction. In other words, in the process of the source local oscillation light being transmitted through the first metal waveguide 225 and the second metal waveguide 226, each of the N2 nanoslot antenna groups 227 radiates the light field of the first polarization state and the light field of the second polarization state toward the polarization beam splitter 23 due to resonance. The light field of the first polarization state and the light field of the second polarization state radiated by each nanoslot antenna group are combined into the first local oscillation light transmitted to the polarization beam splitter 23 through the spatial light field.

[0073] Preferably, in actual design, in order to improve the receiving and conversion efficiency of the polarization decomposer 22, the emission direction of the source local oscillation light should be perpendicular to the first end face and the second end face, that is, the source local oscillation light should be irradiated vertically on the first end face and the second end face. In order to improve the transmission efficiency of the first local oscillation light between the polarization decomposer 22 and the polarization beam splitter 23, the second plane should also be perpendicular to the direction of the optical port on the polarization beam splitter 23 for receiving the first local oscillation light, that is, the first local oscillation light should be irradiated vertically on the optical port on the polarization beam splitter 23 for receiving the first local oscillation light.

[0074] Optionally, the present application does not impose any specific restrictions on the shapes and materials of the first metal waveguide 225 and the second metal waveguide 226, as long as the N2 nanoslot antenna groups can be etched on the surface of the first metal waveguide 225 and / or the second metal waveguide 226 facing the polarization beam splitter 23. For example, the first metal waveguide 225 and the second metal waveguide 226 may be a rectangular parallelepiped or cylindrical structure, and the material thereof may be gold, silver, or the like.

[0075] In the above implementation, the double-ridge waveguide structure constructed by the metal film 224, the first metal waveguide 225 and the second metal waveguide 226 receives and conducts the source local oscillation light, and then the N2 nanoslot antenna groups etched on the first metal waveguide 225 and / or the second metal waveguide 226 convert the first local oscillation light, thereby realizing the function of the polarization decomposer 22. This implementation is relatively simple and has a passive structure, which can make the polarization decomposer 22 have low cost and power consumption, so that the polarization fading problem of the local oscillation light in the self-coherent optical communication system can be solved at low cost and low power consumption, and the applicability and practicality of the entire self-coherent optical communication system can be improved.

[0076] The following will take any one of the N2 nanoslot antenna groups 228 as an example to describe in detail the specific structure and function of each of the N2 nanoslot antenna groups.

[0077] For further information, please see Figure 4 ,like Figure 4 As shown, the nanoslot antenna group 228 may include a first nanoslot antenna 2281 and a second nanoslot antenna 2282 that are perpendicular to each other on the second surface. Figure 4 The fifth axial direction in the nanoslot antenna 2282) Figure 4The sixth axial direction in the direction of the polarization beam splitter 23) are perpendicular to each other on the second surface. It should be noted here that the first nanoslot antenna 2281 and the second nanoslot antenna 2282 are groove structures etched on the surface of the first metal waveguide 225 or the second metal waveguide 226 facing the polarization beam splitter 23. The shape of the groove structure can be a rectangular parallelepiped, a cylinder, etc., and the present application does not impose specific restrictions on this. The size (such as length, width, depth, etc.) of the first nanoslot antenna 2281 and the second nanoslot antenna 2282 is determined by the size of the first wavelength of the above-mentioned source local oscillation light and the first polarization state and the second polarization state of the radiation light field that the nanoslot antenna group 228 needs to support. In other words, the size of the first nanoslot antenna 2281 and the second nanoslot antenna 2282 can be an empirical value obtained by conducting multiple experiments on the nanoslot antenna group 228 based on the size of the first wavelength and the first polarization state and the second polarization state that the nanoslot antenna group 228 needs to support. The first nanoslot antenna 2281 and the second nanoslot antenna 2282 etched with the empirical value can radiate the light field of the first polarization state and the second polarization state under the action of the first wavelength of light. It should be understood that the embodiment of the present application will not specifically limit the shape and size of the first nanoslot antenna 2281 and the second nanoslot antenna 2282. As long as the nanoslot antenna is etched on the first metal waveguide 225 or the second metal waveguide 226 and can radiate the first polarization state or the second polarization state toward the polarization beam splitter 23, it is within the protection scope of the present application.

[0078] In practical applications, when the source local oscillation light is transmitted through the first metal waveguide 225 and the second metal waveguide 226, due to the scattering effect of the metal edge, the first nanoslot antenna 2281 can radiate a light field of the first polarization state to the polarization beam splitter 23, and the second nanoslot antenna 2282 can radiate a light field of the second polarization state to the polarization beam splitter 23.

[0079] Preferably, in actual implementation, the distance between the first nanoslot antenna 2281 and the second nanoslot antenna 2282 on the second plane can be set as a target preset distance, so that the light intensity of the light field of the first polarization state radiated outward by the first nanoslot antenna 2281 is the same as the light intensity of the light field of the second polarization state radiated outward by the second nanoslot antenna 2282. Here, the target preset distance is an empirical value obtained by performing multiple experiments on the first nanoslot antenna 2281 and the second nanoslot antenna 2282. Here, setting the distance between the first metal waveguide 225 and the second metal waveguide 226 on the second plane as the target preset distance can make the light intensity of the light field radiated by the nanoslot antenna group 228 in the first polarization state and the second polarization state evenly divided. When each of the N2 nanoslot antenna groups adopts the same setting, the light intensity of the first local oscillation light in the first polarization state and the second polarization state can be made the same, which can facilitate the subsequent mixing processing of the coherent optoelectronic processing module 24.

[0080] In the above implementation, two mutually perpendicular nanoslot antennas are used to form a nanoslot antenna group. This method is simple and easy to implement, and can further reduce the design and production costs of the polarization decomposer 22 .

[0081] For further information, see Figure 5 , Figure 5 FIG. 1 is another structural diagram of a coherent optical receiving device provided in an embodiment of the present application. Figure 5 As shown, the polarization splitter 22 adopts Figure 4 In the structure shown in FIG. 1 , the coherent optical receiving device 20 may further include a first optical interface 291 and a second optical interface 292. One end of the first optical interface 291 is connected to one end of the polarization decomposer 22, and the other end of the polarization decomposer 22 is connected to the polarization beam splitter through the second optical interface 292. Figure 5 As shown, the connection between the first optical interface 291 and the polarization decomposer 22, and the connection between the second optical interface 292 and the polarization decomposer 22 and the polarization beam splitter 23 are all the spatial optical connections described above.

[0082] In the actual light receiving process, the first optical interface 291 can focus the source local oscillation light in the scattered state and transmit the focused source local oscillation light to the polarization decomposer 22, that is, the first optical interface 291 can irradiate the focused source local oscillation light on the first end face of the first metal waveguide 225 and the second end face of the second metal waveguide 226. In this way, the first end face of the first metal waveguide 225 and the second metal waveguide 226 can fully receive the source local oscillation light, which can reduce the light loss caused by the source local oscillation light being transmitted to the polarization decomposer 22 through the spatial light field, and improve the conversion efficiency of the polarization decomposer 22. The second optical interface 292 can focus the first polarized light radiated from the polarization decomposer 22 and transmit the focused first local oscillation light to the polarization beam splitter 23, which can reduce the light loss caused by the first local oscillation light being transmitted between the polarization decomposer 22 and the polarization beam splitter 23 through the spatial light field.

[0083] Optionally, the first optical interface 291 and the second optical interface 292 may specifically be lenses with a light focusing function, which can further reduce the cost of the polarization decomposer 22 .

[0084] For some possible implementations, see Figure 6 , Figure 6 It is another structural schematic diagram of a coherent optical receiving device provided in an embodiment of the present application. As shown in Figure 6, the above-mentioned signal light receiving module 21 may specifically include a polarization beam splitter 211. The above-mentioned coherent photoelectric processing module 24 may specifically include a mixer 241, a mixer 242, a photodetector 243, a photodetector 244, a photodetector 245 and a photodetector 246. Among them, the polarization beam splitter 211 is connected to the mixer 241 and the mixer 242 respectively, and the polarization beam splitter 23 is also connected to the mixer 241 and the mixer 242 respectively. The mixer 241 is also connected to the photodetector 243 and the photodetector 244 respectively. The mixer 242 is also connected to the photodetector 245 and the photodetector 246 respectively. It should be noted here that in the embodiment of the present application, the input signal of each mixer in the coherent photoelectric processing module 24 is two beams of polarized light with the same polarization state. In this way, the structure of the mixer in the coherent photoelectric processing module 24 is relatively simple, easy to design and produce.

[0085] In the actual light receiving process, similar to the function of the polarization beam splitter 23, the polarization beam splitter 211 can receive the source signal light, and polarization split the source signal light to obtain the first polarization light of the first polarization state and the second polarization light of the second polarization state. Then, the polarization beam splitter 211 can transmit the first polarization light to the mixer 241, and transmit the second polarization light to the mixer 242. In addition, the polarization beam splitter 23 will also process to obtain the third polarization light of the first polarization state and the fourth polarization light of the second polarization state, and transmit the third polarization light to the mixer 241, and transmit the fourth polarization light to the mixer 242. After the mixer 241 receives the first polarization light and the third polarization light, it can perform beat frequency processing on the first polarization light and the third polarization light to obtain two corresponding coherent light signals (here it is assumed that the first coherent light signal and the second coherent light signal are included). Then, the mixer 241 can transmit the first coherent light signal to the photodetector 243, and transmit the second coherent light signal to the photodetector 244. The photodetector 243 can convert the first coherent optical signal into a corresponding first coherent electrical signal and output it. The photodetector 244 can convert the second coherent optical signal into a corresponding second coherent electrical signal and output it. Similarly, after the mixer 242 receives the second polarized light and the fourth polarized light, the second polarized light and the fourth polarized light can be subjected to beat frequency processing to obtain two corresponding coherent optical signals (here it is assumed that the third coherent optical signal and the fourth coherent optical signal are included). Then, the mixer 241 can transmit the third coherent optical signal to the photodetector 245 and the fourth coherent optical signal to the photodetector 246. The photodetector 245 can convert the third coherent optical signal into a corresponding third coherent electrical signal and output it. The photodetector 246 can convert the fourth coherent optical signal into a corresponding fourth coherent electrical signal and output it. Here, the above-mentioned first coherent electrical signal, the second coherent electrical signal, the third coherent electrical signal and the fourth coherent electrical signal are multiple coherent electrical signals output by the coherent photoelectric processing module 24.

[0086] It should be noted here that the coherent optoelectronic processing module 24 is a commonly used structure in self-coherent optical communication technology, which is mainly used to receive two processed local oscillator lights and two processed signal lights, and perform frequency mixing and optoelectronic conversion on these four light beams, and output multiple coherent electrical signals with a certain relationship, so as to prepare for the subsequent further acquisition of transmission content. In actual applications, the coherent optoelectronic processing module can output four or eight coherent electrical signals, or other numbers of coherent electrical signals, which needs to be determined according to actual application requirements, and this application does not impose specific restrictions on this. Therefore, it needs to be understood that Figure 6The specific structure of the coherent optoelectronic processing module 24 shown is only an example, and those skilled in the art can adopt other existing or new structures of the coherent optoelectronic processing module 24 according to the actual application needs. Therefore, the specific structure of the coherent optoelectronic processing module mentioned in this application and other deformations that can be easily thought of by those skilled in the art should be regarded as within the scope of protection of this application. In addition, the mixer involved in the embodiment of the present application is actually an optical mixer for coherent optical communication. In practical applications, the mixer can be implemented by spatial optical elements or silicon optical materials. For example, multi-mode interference (MMI) mixer, coupler array mixer, etc. Therefore, unless otherwise specified, the mixer currently used in coherent optical communication, and the new mixer realized with the development of optical materials in the future can be used in the coherent optoelectronic processing module 24 provided in the embodiment of the present application.

[0087] It should also be noted that in the embodiments of the present application, the specific description of a certain technical feature in a certain implementation can also be used to explain the corresponding technical features mentioned in other implementations. Figure 4 and Figure 5 Two different structures of polarization splitter 22 are described, both of which are suitable for Figure 2 or Figure 6 The polarization decomposer 22 shown in FIG. That is, in the embodiments of the present application, the different specific structures of the devices or modules can be combined with each other, and the solutions obtained by these combinations should be considered to be within the protection scope of the present application. In addition, in the description of the embodiments of the present application, the description from the perspective of the light beam flow is to more clearly describe the structure and function of the device, and cannot be understood as a limitation on the device itself.

[0088] In the embodiment of the present application, the source local oscillator light signal of any polarization state is first processed by a passive optical device-polarization decomposer 22 with a simple structure to obtain a first local oscillator light with light intensity in both the first polarization state and the second polarization state, and then the first local oscillator light is split by a polarization beam splitter 23 to obtain a third polarization light and a fourth polarization light with both light intensities not being zero. The polarization decomposer 22 makes the local oscillator light input to the polarization beam splitter 23 have light in both the first polarization state and the second polarization state, thereby effectively solving the polarization fading problem of the local oscillator light in the self-coherent optical communication system. In addition, the above-mentioned polarization decomposer 22 is a passive optical device with a simple structure, which can effectively solve the polarization fading problem of the local oscillator light while reducing the cost and power consumption of the coherent optical receiving device, and can significantly improve the applicability and practicality of the self-coherent optical communication system.

[0089] Embodiment 2

[0090] See also Figure 7 , Figure 7 is a flow chart of a coherent light receiving method provided in an embodiment of the present application. The coherent light receiving method is applicable to the coherent light receiving device 20 described in the above embodiment. In this embodiment, the specific structure and function of the coherent light receiving device 20 can be found in the corresponding description in the above embodiment 1, and this embodiment will not be repeated. Figure 7 As shown, the coherent light receiving method can specifically include the following steps:

[0091] S701 , receiving source signal light through a signal light receiving module, generating and outputting first polarized light in a first polarization state and second polarized light in a second polarization state according to the source signal light.

[0092] In some feasible implementations, the coherent optical receiving device 20 can receive the source signal light from the opposite end through the signal light receiving module 21, and then generate and output the first polarization light of the first polarization state and the second polarization light of the second polarization state according to the source signal light through the signal light receiving module 21. Here, the first polarization state and the second polarization state are orthogonal to each other. The specific process of the optical receiving module 21 generating and outputting the first polarization light of the first polarization state and the second polarization light of the second polarization state according to the source signal light can be referred to the corresponding process described in the above embodiment 1, which will not be repeated here.

[0093] S702, receiving source local oscillation light through a polarization decomposer, generating and outputting first local oscillation light according to the source local oscillation light.

[0094] In some feasible implementations, the coherent light receiving device 20 may receive the source local oscillation light from the other end through the polarization decomposer 22 , and then generate and output the first local oscillation light according to the source local oscillation light through the polarization decomposer 22 .

[0095] In an optional specific implementation, the polarization decomposer 22 may include a substrate 221, and N1 polarization decomposition components arranged on the first plane of the substrate 221. Here, the specific structure of the polarization decomposer 22 can be referred to in the above embodiment 1 based on Figure 4 The description of the specific structure of the polarization decomposer 22 will not be repeated here. In this case, when the source local oscillator light irradiates the first plane, the coherent light receiving device 20 can radiate the first local oscillator light to the polarization beam splitter through N1 polarization decomposition components. Each of the N1 polarization decomposition components is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter. The specific process can be referred to the specific process of radiating the first local oscillator light to the polarization beam splitter through N1 polarization decomposition components described above, and will not be repeated here.

[0096] Further, any polarization decomposition component 223 of the N1 polarization decomposition components may include a first metal antenna 2231 and a second metal antenna 2232, and one end of the first metal antenna 2231 is connected to one end of the second metal antenna 2232. In practical applications, when the source local oscillation light irradiates the first plane, the first metal antenna 2231 may radiate the light field of the first polarization state to the polarization beam splitter, and the second metal antenna 2232 may radiate the light field of the second polarization state to the polarization beam splitter.

[0097] Optionally, the axial lengths of the first metal antenna 2231 and the second metal antenna 2232 are determined by the first wavelengths of the source signal light and the source local oscillator light. The transmittance of the substrate for the light of the first wavelength is equal to or greater than a preset transmittance. Here, the description of the structure and function of the first metal antenna 2231, the second metal antenna 2232 and the substrate 221 can be referred to the corresponding description in the first embodiment, and will not be repeated here.

[0098] In another optional specific implementation, the polarization decomposer 22 includes a metal film 224, a first metal waveguide 225 and a second metal waveguide 226 arranged on the second plane of the metal film 224, and N2 nanoslot antenna groups 227 etched on the first metal waveguide 225 and / or the second metal waveguide 226. Wherein N2 is a positive integer greater than or equal to 1, the second surface is the surface of the metal film 224 facing the polarization beam splitter 23, and the first metal waveguide 225 and the second metal waveguide 226 are parallel to each other on the second surface. Here, the description of the specific structure of the polarization decomposer 22 can be found in the above-mentioned description based on Figure 4 The description of the specific structure of the polarization decomposer 22 will not be repeated here. In this case, when the source local oscillation light irradiates the end faces of the first metal waveguide 225 and the second metal waveguide 226, the polarization decomposer 22 can receive and conduct the source local oscillation light through the first metal waveguide 225 and the second metal waveguide 226. At the same time, it can radiate the first local oscillation light to the polarization beam splitter 23 through the N2 nanoslot antenna groups 227. Each of the N2 nanoslot antenna groups 227 is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter. Here, the specific implementation process of the polarization decomposer 22 receiving and conducting the source local oscillation light through the first metal waveguide 225 and the second metal waveguide 226, and radiating the first local oscillation light to the polarization beam splitter 23 through the N2 nanoslot antenna groups 227 can refer to the corresponding process described in the previous embodiment 1, and will not be repeated here.

[0099] Further, any nanoslot antenna group 228 of the N2 nanoslot antenna groups 227 includes a first nanoslot antenna 2281 and a second nanoslot antenna 2282 that are perpendicular to each other on the second surface. Here, the description of the first nanoslot antenna 2281 and the second nanoslot antenna 2282 can be referred to the corresponding description in the above embodiment one, which will not be repeated here. In practical applications, when the first metal waveguide 225 and the second metal waveguide 226 conduct the source local oscillation light, the first nanoslot antenna 2281 is used to radiate the light field of the first polarization state to the polarization beam splitter, and the second nanoslot antenna 2282 is used to radiate the light field of the second polarization state to the polarization beam splitter. The specific implementation process can be referred to the corresponding process described in the above embodiment one, which will not be repeated here.

[0100] Optionally, the distance between the first nanoslot antenna 2281 and the second nanoslot antenna 2282 on the second plane is a target preset distance, so that the intensity of the light field in the first polarization state radiated by the first nanoslot antenna 2281 is the same as the intensity of the light field in the second polarization state radiated by the second nanoslot antenna 2282.

[0101] Optionally, the sizes of the first nanoslot antenna 2281 and the second nanoslot antenna 2282 are determined by the first wavelengths of the source signal light and the source local oscillator light.

[0102] In some optional implementations, the above-mentioned coherent light receiving device 20 may also include a first optical interface 291. The first optical interface is connected to one end of the polarization decomposer. In the actual light receiving process, the coherent light receiving device 20 can focus the received source local oscillation light through the first optical interface 291 to obtain the focused source local oscillation light. Then, the focused source local oscillation light is received through the polarization decomposer 22. In other words, the above-mentioned first optical interface 291 can focus the source local oscillation light in a scattered state and transmit the focused source local oscillation light to the polarization decomposer 22. In this way, the first end face of the first metal waveguide 225 and the second metal waveguide 226 can fully receive the above-mentioned source local oscillation light, which can reduce the optical loss caused by the transmission of the source local oscillation light to the polarization decomposer 22 through the spatial light field, and improve the conversion efficiency of the polarization decomposer 22.

[0103] S703, receiving the first local oscillation light through a polarization beam splitter, generating and outputting a third polarized light in the first polarization state and a fourth polarized light in the second polarization state according to the first local oscillation light.

[0104] In some feasible implementations, the coherent light receiving device 20 may receive the first local oscillation light through the polarization beam splitter 23, and then generate and output the third polarized light in the first polarization state and the fourth polarized light in the second polarization state to the coherent photoelectric processing module 24 according to the first local oscillation light. The specific implementation process can refer to the corresponding process described in the first embodiment above, and will not be repeated here.

[0105] In an optional implementation, the coherent light receiving device 20 may further include a second optical interface 292. One end of the polarization decomposer 22 is connected to the polarization beam splitter 23 through the second optical interface 292. In practical applications, the coherent light receiving device 20 may focus the received first local oscillation light through the second optical interface 292 and output the focused first local oscillation light. Then, the focused first local oscillation light is received through the polarization beam splitter 23. In this way, the optical loss caused by the transmission of the first local oscillation light between the polarization decomposer 22 and the polarization beam splitter 23 through the spatial light field can be reduced.

[0106] S704, receiving the first polarized light, the second polarized light, the third polarized light and the fourth polarized light through a coherent optoelectronic processing module, and performing frequency mixing and optoelectronic conversion on the first polarized light, the second polarized light, the third polarized light and the fourth polarized light to output a plurality of coherent electrical signals.

[0107] In some feasible implementations, the coherent optical receiving device 20 can receive the first polarized light, the second polarized light, the third polarized light, and the fourth polarized light through the coherent optoelectronic processing module 24, and then mix and photoelectrically convert the first polarized light, the second polarized light, the third polarized light, and the fourth polarized light through the coherent optoelectronic processing module 24 to output multiple coherent electrical signals. Here, the specific process of the coherent optical receiving device 20 receiving the first polarized light, the second polarized light, the third polarized light, and the fourth polarized light through the coherent optoelectronic processing module 24, and mixing and photoelectrically converting the first polarized light, the second polarized light, the third polarized light, and the fourth polarized light to output multiple coherent electrical signals can be referred to the corresponding process described in the first embodiment above, and will not be repeated here.

[0108] In the coherent light receiving method provided in the present application, the coherent light receiving device 20 can first process the source local oscillator light signal of any polarization state through a passive optical device-polarization decomposer 22 with a simple structure to obtain a first local oscillator light with light intensity in both the first polarization state and the second polarization state, and then split the first local oscillator light through a polarization beam splitter 23 to obtain a third polarization light and a fourth polarization light with both light intensities not being zero. In this way, the local oscillator light input by the polarization beam splitter 23 can have light in both the first polarization state and the second polarization state, thereby effectively solving the polarization fading problem of the local oscillator light in the self-coherent optical communication system. In addition, the above-mentioned polarization decomposer 22 is a passive optical device with a simple structure, which can effectively solve the polarization fading problem of the local oscillator light while reducing the cost and power consumption of the coherent light receiving device, and can significantly improve the applicability and practicality of the self-coherent optical communication system.

[0109] The present application also provides a coherent optical receiving device. Figure 8 , Figure 8 is a schematic diagram of the structure of a coherent optical receiving device provided in an embodiment of the present application, such as Figure 8 As shown, the coherent optical receiving device 80 may specifically include the coherent optical receiving device 20 described in the foregoing embodiment 1 or embodiment 2 and an optical signal processor 81 coupled to the coherent optical receiving device 20. In practical applications, the coherent optical receiving device 20 may receive source signal light and source local oscillator light from the opposite end, and generate and output multiple coherent electrical signals based on the source signal light and the source local oscillator light. For the specific process, please refer to the specific process of the coherent optical receiving device 20 generating and outputting multiple coherent electrical signals described in the foregoing embodiment 1, which will not be repeated here. The optical signal processor 81 can be used to receive multiple coherent electrical signals, and further process the multiple coherent electrical signals to complete the coherent demodulation of the source signal light, and then obtain the transmission content carried on the source signal light.

[0110] It should be noted that the above-mentioned optical signal processor 81 can specifically be a digital signal processor, or other types of processors. For example, a general-purpose processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component. The general-purpose processor can be a microprocessor or any conventional processor, etc. In a specific implementation, the program code required for the DSP to implement coherent demodulation of the source signal light according to multiple coherent electrical signals can be stored in a memory. Here, the memory can be a non-volatile memory, such as a hard disk drive (HDD), etc., or a volatile memory (volatile memory), such as a random-access memory (RAM).

[0111] It should also be noted that the above-mentioned coherent optical receiving device 20 and the optical signal processor 81 are the main components included in the above-mentioned coherent optical receiving device 80. In actual use, the coherent optical receiving device 80 may also include other components such as a trans-impedance amplifier (TIA) and an analog digital converter (ADC) to cooperate in completing functions such as coherent demodulation. The structure of the coherent optical receiving device 80 of the present application is not specifically limited.

[0112] The present application also provides a self-coherent optical communication system. Fig. 9 , Fig. 9 FIG. 1 is a schematic diagram of the structure of another self-coherent optical communication system provided in an embodiment of the present application. Fig. 9 As shown, the self-coherent optical communication system 90 may include the coherent optical receiving device 80 as described above, as well as the optical transmitting device 82 and the optical fiber 83. Among them, the optical transmitting device 82 and the coherent optical receiving device 80 are connected through the optical fiber 83. In practical applications, the above-mentioned optical transmitting device 82 is used to generate the above-mentioned source local oscillator light and source signal light, and send the source local oscillator light and the source signal light to the coherent optical receiving device 80 through the optical fiber 83. The coherent optical receiving device 80 can receive the source local oscillator light and the source signal light through the optical fiber 83, and finally determine the transmission content carried on the source signal light according to the source local oscillator light and the source signal light.

[0113] It should be noted here that in practical applications, the two opposite ends of the self-coherent optical communication system are both optical transceiver devices with both optical transmission and optical reception functions, such as Figure 1 The optical transceiver 10 and the optical transceiver 11 in the self-coherent optical communication system shown. The optical transmitting device 82 or the coherent optical receiving device 80 provided in the present application can be used as or replace some functional devices for sending optical signals or receiving optical signals in these optical transceiver devices. For example, for the self-coherent optical communication system shown in 1, the above-mentioned optical transmitting device 82 can replace the light source 101, the splitter 102, the optical modulation module 103, the filter 106 and the filter 107 in the optical transceiver 10 to realize the transmission function of signal light and local oscillation light. The above-mentioned coherent optical receiving device 80 can replace the coherent receiver 105 in the optical transceiver 10 to realize the function of coherent reception of local oscillation light and signal light.

[0114] The specific implementation methods described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the specific implementation methods of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present application should be included in the scope of protection of the present application.

Claims

1. A coherent light receiving device, characterized in that: The coherent optical receiving device comprises: a signal optical receiving module, a polarization decomposer, a polarization beam splitter and a coherent optical-electrical processing module, wherein the coherent optical-electrical processing module is connected to the signal optical receiving module and the polarization beam splitter respectively, and the polarization decomposer is connected to the polarization beam splitter; The signal light receiving module is used to receive the source signal light, generate and output a first polarized light in a first polarization state and a second polarized light in a second polarization state according to the source signal light, wherein the first polarization state is orthogonal to the second polarization state; The polarization decomposer is used to receive the source local oscillation light, generate and output the first local oscillation light according to the source local oscillation light, wherein the light intensity of the first local oscillation light in the first polarization state and the second polarization state is not zero; The polarization beam splitter is used to receive the first local oscillation light, generate and output the third polarized light in the first polarization state and the fourth polarized light in the second polarization state according to the first local oscillation light; The coherent photoelectric processing module is used to receive the first polarized light, the second polarized light, the third polarized light and the fourth polarized light, and perform frequency mixing and photoelectric conversion on the first polarized light, the second polarized light, the third polarized light and the fourth polarized light to output a plurality of coherent electrical signals.

2. The coherent light receiving device according to claim 1, characterized in that: The polarization decomposer comprises a substrate, and N1 polarization decomposition components arranged on a first plane of the substrate, the first plane being a plane of the substrate facing away from the polarization beam splitter, and N1 being a positive integer greater than or equal to 1; When the source local oscillator light illuminates the first plane, the N1 polarization decomposition components are used to radiate the first local oscillator light to the polarization beam splitter, wherein each of the N1 polarization decomposition components is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

3. The coherent light receiving device according to claim 2, characterized in that: Any polarization decomposition component of the N1 polarization decomposition components includes a first metal antenna and a second metal antenna; Wherein, one end of the first metal antenna is connected to one end of the second metal antenna; When the source local oscillator light irradiates the first plane, the first metal antenna is used to radiate the light field of the first polarization state to the polarization beam splitter, and the second metal antenna is used to radiate the light field of the second polarization state to the polarization beam splitter.

4. The coherent light receiving device according to claim 3, characterized in that: The first metal antenna and the second metal antenna are perpendicular to each other on the first plane.

5. The coherent light receiving device according to claim 3 or 4, characterized in that: The axial lengths of the first metal antenna and the second metal antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

6. The coherent light receiving device according to claim 5, characterized in that: The transmittance of the substrate to the light of the first wavelength is equal to or greater than a preset transmittance.

7. The coherent light receiving device according to claim 1, characterized in that: The polarization decomposer includes a metal film, a first metal waveguide and a second metal waveguide arranged on a second plane of the metal film, and N2 nanoslot antenna groups etched on the first metal waveguide and / or the second metal waveguide, wherein N2 is a positive integer greater than or equal to 1, the second plane is a plane of the metal film facing the polarization beam splitter, and the first metal waveguide and the second metal waveguide are parallel to each other on the second plane; When the source local oscillation light irradiates the end faces of the first metal waveguide and the second metal waveguide, the first metal waveguide and the second metal waveguide are used to receive and conduct the source local oscillation light, and the N2 nanoslot antenna groups are used to radiate the first local oscillation light to the polarization beam splitter, wherein each of the N2 nanoslot antenna groups is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

8. The coherent light receiving device according to claim 7, characterized in that: Any one of the N2 nanoslot antenna groups includes a first nanoslot antenna and a second nanoslot antenna that are perpendicular to each other on the second plane; When the first metal waveguide and the second metal waveguide conduct the source local oscillation light, the first nanoslot antenna is used to radiate the light field of the first polarization state to the polarization beam splitter, and the second nanoslot antenna is used to radiate the light field of the second polarization state to the polarization beam splitter.

9. The coherent light receiving device according to claim 8, characterized in that: The distance between the first nanoslot antenna and the second nanoslot antenna on the second plane is a target preset distance, and the light intensity of the light field of the first polarization state radiated by the first nanoslot antenna is the same as the light intensity of the light field of the second polarization state radiated by the second nanoslot antenna.

10. The coherent light receiving device according to claim 8 or 9, characterized in that: The sizes of the first nanoslot antenna and the second nanoslot antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

11. The coherent light receiving device according to claim 10, characterized in that: The coherent optical receiving device further comprises a first optical interface and a second optical interface, wherein the first optical interface is connected to one end of the polarization decomposer, and the other end of the polarization decomposer is connected to the polarization beam splitter through the second optical interface; The first optical interface is used to focus the received source local oscillator light and transmit the focused source local oscillator light to one end of the polarization decomposer; The second optical interface is used to focus the received first local oscillation light and transmit the focused first local oscillation light to the polarization beam splitter.

12. A coherent light receiving method, characterized in that: The method is applicable to a coherent optical receiving device, which comprises: a signal optical receiving module, a polarization decomposer, a polarization beam splitter and a coherent photoelectric processing module, wherein the coherent photoelectric processing module is connected to the signal optical receiving module and the polarization beam splitter respectively, and the polarization decomposer is connected to the polarization beam splitter; The method comprises: Receive source signal light through the signal light receiving module, generate and output first polarized light in a first polarization state and second polarized light in a second polarization state according to the source signal light, wherein the first polarization state is orthogonal to the second polarization state; receiving a source local oscillation light through the polarization decomposer, generating and outputting a first local oscillation light according to the source local oscillation light, wherein the light intensity of the first local oscillation light in the first polarization state and the second polarization state is not zero; receiving the first local oscillation light through the polarization beam splitter, and generating and outputting a third polarized light in the first polarization state and a fourth polarized light in the second polarization state according to the first local oscillation light; The first polarized light, the second polarized light, the third polarized light and the fourth polarized light are received by a coherent photoelectric processing module, and the first polarized light, the second polarized light, the third polarized light and the fourth polarized light are mixed and photoelectrically converted to output a plurality of coherent electrical signals.

13. The method according to claim 12, characterized in that The polarization decomposer comprises a substrate, and N1 polarization decomposition components arranged on a first plane of the substrate, the first plane being a plane of the substrate facing away from the polarization beam splitter, and N1 being a positive integer greater than or equal to 1; The receiving the source local oscillator light through the polarization decomposer, and generating and outputting the first local oscillator light according to the source local oscillator light, comprises: When the source local oscillator light illuminates the first plane, the first local oscillator light is radiated to the polarization beam splitter through the N1 polarization decomposition components, wherein each of the N1 polarization decomposition components is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

14. The method according to claim 13, characterized in that Each of the N1 polarization decomposition components comprises a first metal antenna and a second metal antenna, wherein one end of the first metal antenna is connected to one end of the second metal antenna; The radiating the first local oscillator light to the polarization beam splitter through the N1 polarization decomposition components comprises: The light field of the first polarization state is radiated toward the polarization beam splitter through the first metal antenna of each polarization decomposition component in the N1 polarization decomposition components, and the light field of the second polarization state is radiated toward the polarization beam splitter through the second metal antenna of each polarization decomposition component in the N1 polarization decomposition components, so as to radiate the first local oscillation light toward the polarization beam splitter.

15. The method according to claim 14, characterized in that The first metal antenna and the second metal antenna are perpendicular to each other on the first plane.

16. The method according to claim 14 or 15, characterized in that: The axial lengths of the first metal antenna and the second metal antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

17. The method according to claim 16, characterized in that The transmittance of the substrate to the light of the first wavelength is equal to or greater than a preset transmittance.

18. The method according to claim 12, characterized in that The polarization decomposer includes a metal film, a first metal waveguide and a second metal waveguide arranged on a second plane of the metal film, and N2 nanoslot antenna groups etched on the first metal waveguide and / or the second metal waveguide, where N2 is a positive integer greater than or equal to 1, the second plane is a plane of the metal film facing the polarization beam splitter, and the first metal waveguide and the second metal waveguide are parallel to each other on the second plane; The receiving the source local oscillator light through the polarization decomposer, and generating and outputting the first local oscillator light according to the source local oscillator light, comprises: When the source local oscillation light irradiates the end faces of the first metal waveguide and the second metal waveguide, the source local oscillation light is received and conducted by the first metal waveguide and the second metal waveguide, and the first local oscillation light is radiated to the polarization beam splitter through the N2 nanoslot antenna groups, wherein each of the N2 nanoslot antenna groups is used to radiate the light field of the first polarization state and the light field of the second polarization state to the polarization beam splitter.

19. The method according to claim 18, characterized in that: Each of the N2 nanoslot antenna groups includes a first nanoslot antenna and a second nanoslot antenna that are perpendicular to each other on the second plane; The radiating the first local oscillator light to the polarization beam splitter through the N2 nanoslot antenna groups includes: The light field of the first polarization state is radiated toward the polarization beam splitter through the first nanoslot antenna of each nanoslot antenna group in the N2 nanoslot antenna groups, and the light field of the second polarization state is radiated toward the polarization beam splitter through the second nanoslot antenna of each nanoslot antenna group in the N2 nanoslot antenna groups, so as to radiate the first local oscillation light toward the polarization beam splitter.

20. The method according to claim 19, characterized in that The distance between the first nanoslot antenna and the second nanoslot antenna on the second plane is a target preset distance, and the light intensity of the light field of the first polarization state radiated by the first nanoslot antenna is the same as the light intensity of the light field of the second polarization state radiated by the second nanoslot antenna.

21. The method according to claim 19 or 20, characterized in that The sizes of the first nanoslot antenna and the second nanoslot antenna are determined by the first wavelengths of the source signal light and the source local oscillator light.

22. The method according to claim 21, characterized in that The coherent optical receiving device further comprises a first optical interface and a second optical interface, wherein the first optical interface is connected to one end of the polarization decomposer, and the other end of the polarization decomposer is connected to the polarization beam splitter through the second optical interface; The receiving source local oscillator light through the polarization decomposer includes: Focusing the received source local oscillator light through the first optical interface to obtain focused source local oscillator light; Receiving the focused source local oscillator light through the polarization decomposer; The receiving the first local oscillator light through the polarization beam splitter includes: focusing the received first local oscillator light through the second optical interface and outputting the focused first local oscillator light; The focused first local oscillation light is received through the polarization beam splitter.

23. A coherent optical receiving device, characterized in that: include: A coherent optical receiving device as claimed in any one of claims 1 to 11, and an optical signal processor coupled to the coherent optical receiving device; The optical signal processor is used to receive a plurality of coherent electrical signals output by the coherent optical receiving device, and determine the transmission content carried by the source signal light according to the plurality of coherent electrical signals.

24. A self-coherent optical communication system, characterized in that: The self-coherent optical communication system comprises an optical transmitting device, an optical fiber, and a coherent optical receiving device as claimed in claim 23; Wherein, the optical transmitting device generates and transmits source local oscillator light and source signal light to the coherent optical receiving device through the optical fiber; The coherent optical receiving device receives the source local oscillator light and the source signal light through the optical fiber, and determines the transmission content carried by the source signal light according to the source local oscillator light and the source signal light.

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